Brian Keogh in Tucson

Rory McIlroy has set his sights on challenging for the WGC-Accenture Match Play Championship after a 2 and 1 win over pal Louis Oosthuizen put him a step closer to a third round encounter with world number one Tiger Woods in Tucson.

But it was a disappointing night for the rest of the Irish as third seed Padraig Harrington battled valiantly but lost to Pat Perez by one hole as an under-the-weather Graeme McDowell crashed out to Zach Johnson by 3 and 1.

"I think my game is right there but I didn't give myself the chances today and I was not as sharp as I could have been," a crestfallen Harrington said after losing in the first round for a fourth time.

"I lost it on the fifth hole. I missed a putt there and made a terrible five from the middle of the fairway when he was in trouble.

"Everything after that was a bit of a struggle. I had a few putts here and there but that was a momentum shift there."

But if Harrington was bitterly disappointed, McIlroy was smiling after a bitter-sweet victory over his ISM stablemate Oosthuizen.

“I found it quite difficult because Louis is a good friend of mine and it is always difficult to play someone you know quite well,” McIlroy said. “Neither of us played as well as we could  but I was able to make my pars when I needed to and I got the job done. I feel that if I can go on and get rolling, with the way I play, I would be able to go quite far in this tournament.”

McIlroy could meet Woods in tomorrow’s third round if he beats US Ryder Cup star Hunter Mahan today and the world number one comes through against Tim Clark. But the 19-year-old Holywood talent refused to get ahead of himself and headed straight to the range to work on his distance control.

“Tiger’s still got to win his second round match,” McIlroy said with an impish grin. “But it is a long way off before that happens. It is not on my mind, not at all. All I can do is concentrate on my match tomorrow.

“Hopefully I will play a bit better. I drove the ball great and missed just one fairway. But it is hard to control your distance out here because the ball is travelling so far so I will work on some half shots on the range.

“You got to accept that if you hit a really good shot here it might end up 50 feet away.  There's so much slope on the greens. So you got to be very patient and bide your time, and if you're hitting good shots and not getting crazy, you just got to keep plodding away and keep dealing with it.”

McIlroy went one up with a conceded birdie at the second and while he lost the third after finding water with his tee shot, he was to strong for his stable mate from tee to green.

A birdie-par run at the eighth and ninth put him two up at the turn and while he lost the short 12th to a par he bounced back with a winning birdie at the par-five 13th and then closed out the match by drawing on his amateur experiences.

“Playing the Close and the West of Ireland does help and most of those were 18 hole singles matches as well,” he said. “So it’s a bit of a sprint and you need to get off to a fast start and I am playing with three of four years of that and I think that experience will help me this week.”

McDowell was simply outgunned on the greens by Johnson, who closed out a 3 and 1 victory thanks to a couple of stunning iron shots at the 16th and 17th.

Struggling to shake off cold and flu symptoms, the Ulsterman halved the first two holes in birdie but found himself two down with 10 to play when he lost the seventh to par and then conceded Johnson a winning eagle three at the eighth and never recovered.

Disappointed with his performance, McDowell said: "I wasn't really on top of my game today. I had a bit of cold and flu on me this week and I haven't really been feeling 100 percent. thought I was shaking it off but I am not making excuses.

“Zach played great and I think he made eight birdies in 17 holes. That is pretty strong  stuff. I tried my best to hang in and I had my chances. I burned the edge with a few putts and never quite had it going today. I was behind the eight ball early doors and Zach gave me a couple of openings but I just wasn't able to take advantage.”

Coming off missed cuts at Pebble Beach and Riviera, Harrington gave fair warning that it would be a long day at the office when he lost the first to a par after a wild drive into the desert.

In fact, he could easily have found himself two down after two where Perez hit his approach to a foot at the 574-yard par-five before the Dubliner salvaged a half by spectacularly holing a 40-yard pitch for a matching eagle three

One down at the turn, he squared the match at the 11th but lost the 12th to a Perez birdie two and then missed a short putt for a half at the 13th to find himself two down with five to play.

A clutch par putt at the driveable 15th, where he had to drop out of the desert, kept him alive and he then drained an 18 footer for a two at the 16th to cut the gap to just one hole with two to play against the man from nearby Phoenix.

At the 17th, Harrington was in trouble off the tee but holed a lengthy putt for a half in par to take the match down the 18th.

Bunkered off the tee and with Perez just 20 feet away in two, Harrington hit a stunning nine iron over the flag to nine feet.

Perez missed his birdie chance for the match but he was soon into the second round as the Irish superstar's putt to force extra holes slid by on the low side.